Young Muslims are being taught extremist views in British mosques, an undercover investigation has found.

Shocking footage of children apparently being hit by their teachers during lessons on the Koran will also be aired on Channel 4's Dispatches programme on Monday.

A hidden camera installed by a reporter at a school in Birmingham recorded a preacher telling pupils "the disbelievers are the worst creatures, they are the worst creatures".

The 11-year-olds are then told not to trust more liberal Muslims.

Their teacher said: "The person who's got less than a fistful of beard, then you should stay away from him the same way you should stay away from a serpent or a snake."

Another group of pupils are told in an assembly at the school: "The disbelievers, they are the worst of all people. The Hindus do, they drink piss, I've told you this. Do they have any intellect? No."

The school is inspected by Government-approved teams and is required to teach tolerance and respect for other religions.

Access to the school was gained when the undercover investigator got a job as a volunteer in 2009. He was allowed to sit in on some lessons, but he was not let into Islamic classes. In July last year, he went into one of the rooms where he heard Islamic studies was being taught and he left a secret camera.

In more footage filmed by the programme at a mosque in Yorkshire, teenagers and a preacher are seen to be hitting younger children. Pupils as young as six or seven were caught on camera being hit and kicked by the people supposed to be looking after them.

Dr Taj Hargey, founder of the Muslim Educational Centre of Oxford, said: "This is totally against Islam. This is something that is deeply humiliating and shameful to Muslims to hear other Muslims describe people of other religions in such derogatory, disparaging terms."